Messages in this thread | | | Subject | Re: [NEEDS-REVIEW] [PATCH v15 03/26] x86/fpu/xstate: Introduce CET MSR XSAVES supervisor states | From | Dave Hansen <> | Date | Mon, 30 Nov 2020 10:12:53 -0800 |
| |
On 11/30/20 10:06 AM, Yu, Yu-cheng wrote: >>> + if (!boot_cpu_has(X86_FEATURE_SHSTK) && >>> + !boot_cpu_has(X86_FEATURE_IBT)) >>> + xfeatures_mask_all &= ~BIT_ULL(i); >>> + } else { >>> + if ((xsave_cpuid_features[i] == -1) || >> >> Where did the -1 come from? Was that introduced earlier in this series? >> I don't see any way a xsave_cpuid_features[] can be -1 in the >> current tree. > > Yes, we used to have a hole in xsave_cpuid_features[] and put -1 there. > Do we want to keep this in case we again have holes in the future?
So, it's dead code for the moment and it's impossible to tell what -1 means without looking at git history? That seems, um, suboptimal.
Shouldn't we have:
#define XFEATURE_NO_DEP -1
?
And then this code becomes:
if ((xsave_cpuid_features[i] == XFEATURE_NO_DEP)) // skip it...
We can even put a comment in xsave_cpuid_features[] to tell folks to use it.
| |